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1.
Pol J Vet Sci ; 27(1): 85-94, 2024 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-38511625

RESUMO

Anaplasmosis and ehrlichiosis are important tick-borne rickettsial diseases of medical and veterinary importance that cause economic losses in livestock. In this study, the prevalence of Anaplasma ovis, Ehrlichia canis and Ehrlichia chaffeensis was investigated in ticks collected from sheep in various farms in Van province, which is located in the Eastern Anatolian Region of Turkey. The ticks used in this study were collected by random sampling in 26 family farm business in 13 districts of Van province. A total of 688 ticks were collected from 88 sheep and 88 tick pools were created. All ticks identified morphologically as Rhipicephalus bursa. Phylogenetic analysis of Chaperonin and 16S rRNA gene sequences confirmed A. ovis, E. canis and E. chaffeensis in this study. Of the 88 tick pools tested, 28.41% (25/88) were positive for at least one pathogen. Anaplasma DNA was detected in five of the 88 pools (5.68%), E. canis DNA was detected in 19 of the 88 pools (21.59%), and E. chaffeensis DNA was detected in one of the 88 pools (1.14%) of R. bursa ticks. To our knowledge, this is the first report describing the presence of A. ovis, E. canis, and E. chaffeensis in R. bursa ticks collected from sheep in Turkey. Further studies are needed to investigate other co-infections in sheep in Turkey.


Assuntos
Anaplasma ovis , Ehrlichia chaffeensis , Rhipicephalus , Animais , Ovinos/genética , Rhipicephalus/genética , Ehrlichia chaffeensis/genética , Ehrlichia canis/genética , Anaplasma ovis/genética , Turquia/epidemiologia , RNA Ribossômico 16S/genética , Filogenia , DNA
2.
J Am Chem Soc ; 146(10): 6706-6720, 2024 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-38421812

RESUMO

Two-dimensional (2D) halide perovskites are exquisite semiconductors with great structural tunability. They can incorporate a rich variety of organic species that not only template their layered structures but also add new functionalities to their optoelectronic characteristics. Here, we present a series of new methylammonium (CH3NH3+ or MA)-based 2D Ruddlesden-Popper perovskites templated by dimethyl carbonate (CH3OCOOCH3 or DMC) solvent molecules. We report the synthesis, detailed structural analysis, and characterization of four new compounds: MA2(DMC)PbI4 (n = 1), MA3(DMC)Pb2I7 (n = 2), MA4(DMC)Pb3I10 (n = 3), and MA3(DMC)Pb2Br7 (n = 2). Notably, these compounds represent unique structures with MA as the sole organic cation both within and between the perovskite sheets, while DMC molecules occupy a tight space between the MA cations in the interlayer. They form hydrogen-bonded [MA···DMC···MA]2+ complexes that act as spacers, preventing the perovskite sheets from condensing into each other. We report one of the shortest interlayer distances (∼5.7-5.9 Å) in solvent-incorporated 2D halide perovskites. Furthermore, the synthesized crystals exhibit similar optical characteristics to other 2D perovskite systems, including narrow photoluminescence (PL) signals. The density functional theory (DFT) calculations confirm their direct-band-gap nature. Meanwhile, the phase stability of these systems was found to correlate with the H-bond distances and their strengths, decreasing in the order MA3(DMC)Pb2I7 > MA4(DMC)Pb3I10 > MA2(DMC)PbI4 ∼ MA3(DMC)Pb2Br7. The relatively loosely bound nature of DMC molecules enables us to design a thermochromic cell that can withstand 25 cycles of switching between two colored states. This work exemplifies the unconventional role of the noncharged solvent molecule in templating the 2D perovskite structure.

3.
J Fr Ophtalmol ; 47(3): 104015, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38129198

RESUMO

PURPOSE: To evaluate the retinal, choroidal, and optic disc head microvascular circulation in human immunodeficiency virus (HIV)-infected individuals without retinopathy receiving highly active antiretroviral therapy (HAART) using swept-source optical coherence tomography angiography (SS-OCTA). METHODS: This cross-sectional study included 100 eyes of 100 patients with HIV infection but no HIV-related ocular disease and 108 eyes of 108 age- and sex-matched healthy subjects as the control group. SS-OCTA was used to assess foveal avascular zone (FAZ) area, retinal nerve fiber layer thickness (RNFL), choriocapillaris (CC) flow area, outer retinal (OR) thickness, radial peripapillary capillary (RPC) vessel density (VD), ONH VD, and choroidal thickness. RESULTS: No statistically significant difference was found between the two groups except in the foveal VD of the deep capillary plexus (DCP). The foveal VD of the DCP was lower in the HIV-positive group (P=0.011). The mean FAZ area (mm2), perimeter (mm), and CC flow area (mm) values were higher in the HIV-positive group at statistically significant levels (P=0.021, P=0.02, and P=0.039, respectively). However, no statistically significant differences were found between the two groups concerning the OR flow area, subfoveal choroidal thickness, or the VDs of the RPC or ONH. CONCLUSIONS: This is the first study in the literature to evaluate the microvascular circulation of the ONH in HIV-positive patients. Although retinal and choroidal microvascular circulation decreased in HIV-positive patients receiving HAART treatment, we found no effect on the microvascular circulation of the ONH or RPC microvascular circulation. Our findings suggest that retinochoroidal microvascular circulation is affected in HIV-positive patients over time.


Assuntos
Infecções por HIV , Soropositividade para HIV , Disco Óptico , Humanos , Disco Óptico/diagnóstico por imagem , Tomografia de Coerência Óptica , Infecções por HIV/complicações , Infecções por HIV/tratamento farmacológico , Estudos Transversais , Voluntários Saudáveis , Microcirculação , Angiografia , Vasos Retinianos/diagnóstico por imagem , Angiofluoresceinografia
4.
Pol J Vet Sci ; 26(3): 359-366, 2023 09 20.
Artigo em Inglês | MEDLINE | ID: mdl-37727051

RESUMO

Cryptosporidium spp., and Giardia duodenalis are intestinal protozoan parasites known to infect humans and various animals and cause diarrhea. This study aimed at determining the prevalence and genotype of Cryptosporidium spp. and Giardia duodenalis in sheep in different locations of Siirt province. The fecal material for this study was collected from 500 sheep in different locations of Siirt province, Turkey. Fecal samples obtained from sheep were examined for Cryptosporidium spp. by Kinyoun Acid Fast staining and the Nested PCR method. Microscopic and Nested PCR methods revealed a prevalence of 2.4% (12/500) and 3.6% (18/500), respectively. Sequence analysis revealed the presence of C. ryanae, C. andersoni, and zoonotic C. parvum. In terms of Giardia duodenalis, 8.4% (42/500) and 10.2% (51/500) prevalence was determined using Nativ-Lugol and Nested PCR methods, respectively. Using sequence analysis, zoonotic assemblages A and B as well as assemblages E and D were detected. As a result of this study, both the prevalence of Cryptosporidium spp. and Giardia duodenalis and the presence of species that appear to be host-specific, as well as those known to be zoonotic, were revealed. A large-scale study is needed to understand the impact of these agents on sheep farming and their consequences on human health.


Assuntos
Criptosporidiose , Cryptosporidium , Giardia lamblia , Doenças dos Ovinos , Humanos , Animais , Ovinos , Giardia lamblia/genética , Turquia/epidemiologia , Criptosporidiose/epidemiologia , Cryptosporidium/genética , Genótipo , Doenças dos Ovinos/epidemiologia
5.
Phys Med Biol ; 68(19)2023 09 22.
Artigo em Inglês | MEDLINE | ID: mdl-37735967

RESUMO

Purpose. Commercial electron FLASH platforms deliver ultra-high dose rate doses at discrete combinations of pulse parameters including pulse width (PW), pulse repetition frequency (PRF) and number of pulses (N), which dictate unique combinations of dose and dose rates. Additionally, collimation, source to surface distance, and airgaps also vary the dose per pulse (DPP). Currently, obtaining pulse parameters for the desired dose and dose rate is a cumbersome manual process involving creating, updating, and looking up values in large spreadsheets for every treatment configuration. This work presents a pulse parameter optimizer application to match intended dose and dose rate precisely and efficiently.Methods. Dose and dose rate calculation methods have been described for a commercial electron FLASH platform. A constrained optimization for the dose and dose rate cost function was modelled as a mixed integer problem in MATLAB (The MathWorks Inc., Version9.13.0 R2022b, Natick, Massachusetts). The beam and machine data required for the application were acquired using GafChromic film and alternating current current transformers (ACCTs). Variables for optimization included DPP for every collimator, PW and PRF measured using ACCT and airgap factors.Results. Using PW, PRF,Nand airgap factors as parameters, a software was created to optimize dose and dose rate, reaching the closest match if exact dose and dose rates are not achievable. Optimization took 20 s or less to converge to results. This software was validated for accuracy of dose calculation and precision in matching prescribed dose and dose rate.Conclusion. A pulse parameter optimization application was built for a commercial electron FLASH platform to increase efficiency in dose, dose rate, and pulse parameter prescription process. Automating this process reduces safety concerns associated with manual look up and calculation of these parameters, especially when many subjects at different doses and dose rates are to be safely managed.


Assuntos
Eletricidade , Elétrons , Humanos , Frequência Cardíaca , Software
6.
J Phys Chem Lett ; 14(27): 6309-6314, 2023 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-37405449

RESUMO

A rotating organic cation and a dynamically disordered soft inorganic cage are the hallmark features of organic-inorganic lead-halide perovskites. Understanding the interplay between these two subsystems is a challenging problem, but it is this coupling that is widely conjectured to be responsible for the unique behavior of photocarriers in these materials. In this work, we use the fact that the polarizability of the organic cation strongly depends on the ambient electrostatic environment to put the molecule forward as a sensitive probe of the local crystal fields inside the lattice cell. We measure the average polarizability of the C/N-H bond stretching mode by means of infrared spectroscopy, which allows us to deduce the character of the motion of the cation molecule, find the magnitude of the local crystal field, and place an estimate on the strength of the hydrogen bond between the hydrogen and halide atoms. Our results pave the way for understanding electric fields in lead-halide perovskites using infrared bond spectroscopy.

7.
Microorganisms ; 11(6)2023 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-37374947

RESUMO

The accumulation of xenobiotic compounds in different environments interrupts the natural ecosystem and induces high toxicity in non-target organisms. Diclofenac is one of the commonly used pharmaceutical drugs that persist in the environment due to its low natural degradation rate and high toxicity. Therefore, this study aimed to isolate potential diclofenac-degrading bacteria, detect the intermediate metabolites formed, and determine the enzyme involved in the degradation process. Four bacterial isolates were selected based on their ability to utilize a high concentration of diclofenac (40 mg/L) as the sole carbon source. The growth conditions for diclofenac degradation were optimized, and bacteria were identified as Pseudomonas aeruginosa (S1), Alcaligenes aquatilis (S2), Achromobacter spanius (S11), and Achromobacter piechaudii (S18). The highest percentage of degradation was recorded (97.79 ± 0.84) after six days of incubation for A. spanius S11, as analyzed by HPLC. To detect and identify biodegradation metabolites, the GC-MS technique was conducted for the most efficient bacterial strains. In all tested isolates, the initial hydroxylation of diclofenac was detected. The cleavage step of the NH bridge between the aromatic rings and the subsequent cleavage of the ring adjacent to or in between the two hydroxyl groups of polyhydroxylated derivatives might be a key step that enables the complete biodegradation of diclofenac by A. piechaudii S18, as well as P. aeruginosa S1. Additionally, the laccase, peroxidase, and dioxygenase enzyme activities of the two Achromobacter strains, as well as P. aeruginosa S1, were tested in the presence and absence of diclofenac. The obtained results from this work are expected to be a useful reference for the development of effective detoxification bioprocesses utilizing bacterial cells as biocatalysts. The complete removal of pharmaceuticals from polluted water will stimulate water reuse, meeting the growing worldwide demand for clean and safe freshwater.

8.
Phys Rev Lett ; 130(10): 106901, 2023 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-36962044

RESUMO

Lead halide perovskites enjoy a number of remarkable optoelectronic properties. To explain their origin, it is necessary to study how electromagnetic fields interact with these systems. We address this problem here by studying two classical quantities: Faraday rotation and the complex refractive index in a paradigmatic perovskite CH_{3}NH_{3}PbBr_{3} in a broad wavelength range. We find that the minimal coupling of electromagnetic fields to the k·p Hamiltonian is insufficient to describe the observed data even on the qualitative level. To amend this, we demonstrate that there exists a relevant atomic-level coupling between electromagnetic fields and the spin degree of freedom. This spin-electric coupling allows for quantitative description of a number of previous as well as present experimental data. In particular, we use it here to show that the Faraday effect in lead halide perovskites is dominated by the Zeeman splitting of the energy levels and has a substantial beyond-Becquerel contribution. Finally, we present general symmetry-based phenomenological arguments that in the low-energy limit our effective model includes all basis coupling terms to the electromagnetic field in the linear order.

9.
Nat Commun ; 13(1): 3905, 2022 07 07.
Artigo em Inglês | MEDLINE | ID: mdl-35798732

RESUMO

Whole-cell screening for Mycobacterium tuberculosis (Mtb) inhibitors is complicated by the pathogen's slow growth and biocontainment requirements. Here we present a synthetic biology framework for assaying Mtb drug targets in engineered E. coli. We construct Target Essential Surrogate E. coli (TESEC) in which an essential metabolic enzyme is deleted and replaced with an Mtb-derived functional analog, linking bacterial growth to the activity of the target enzyme. High throughput screening of a TESEC model for Mtb alanine racemase (Alr) revealed benazepril as a targeted inhibitor, a result validated in whole-cell Mtb. In vitro biochemical assays indicated a noncompetitive mechanism unlike that of clinical Alr inhibitors. We establish the scalability of TESEC for drug discovery by characterizing TESEC strains for four additional targets.


Assuntos
Alanina Racemase , Mycobacterium tuberculosis , Alanina Racemase/química , Alanina Racemase/metabolismo , Antituberculosos/química , Antituberculosos/farmacologia , Descoberta de Drogas , Escherichia coli/genética , Escherichia coli/metabolismo , Ensaios de Triagem em Larga Escala , Mycobacterium tuberculosis/metabolismo
10.
J Fr Ophtalmol ; 45(1): 81-92, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34895760

RESUMO

PURPOSE: To analyze the macular microvascular (MMV) architecture, radial peripapillary capillary (RPC) network and choriocapillaris using optical coherence tomography angiography (OCT-A) in patients with systemic sclerosis (SSc) without systemic comorbidities. METHODS: The vessel densities (VDs) of the MMV, foveal avascular zone (FAZ) parameters, choriocapillaris flow areas (CCFAs), RPC VDs, and optic nerve head (ONH) parameters were measured by OCT-A. Retinal thickness and subfoveal choroidal thickness (SFCT) were measured by spectral-domain optical coherence tomography (SD-OCT). The SD-OCT and OCT-A measurements of 53 eyes of 30 SSc patients were compared with 61 eyes of 33 healthy controls. RESULTS: In the MMV analysis, a decrease in the VDs of the superficial capillary plexus and an increase in the FAZ area, FAZ perimeter and non-flow area were detected in the SSc group compared to the controls (P=0.007, P=0.001, P=0.029, P=0.018, and P=0.039, respectively). While there was a decrease in SFCT, no change was found in CCFA (P=0.001 and P=0.902, respectively). The RPC analysis revealed a decrease in the VDs of all vessels for the entire area and the intradisc area, as well as the VDs of the small vessels for the intradisc area (P=0.021, P=0.001, and P=0.003, respectively). In the ONH analysis, there was an increase in the C/D area ratios and cup volumes, and a decrease in the rim areas and nasal quadrant retinal nerve fiber layer thickness (P=0.004, P=0.004, P=0.013, and P=0.032, respectively). CONCLUSION: Decreases in RPC and MMV VDs and changes in ONH parameters were found in OCT-A measurements in patients with SSc.


Assuntos
Escleroderma Sistêmico , Tomografia de Coerência Óptica , Corioide/diagnóstico por imagem , Angiofluoresceinografia , Humanos , Microvasos/diagnóstico por imagem , Vasos Retinianos/diagnóstico por imagem , Escleroderma Sistêmico/complicações , Escleroderma Sistêmico/diagnóstico por imagem
11.
Biomed Phys Eng Express ; 8(1)2021 11 23.
Artigo em Inglês | MEDLINE | ID: mdl-34768242

RESUMO

A 3-D dosimeter fills the need for treatment plan and delivery verification required by every modern radiation-therapy method used today. This report summarizes a proof-of-concept study to develop a water-equivalent solid 3-D dosimeter that is based on novel radiation-hard scintillating material. The active material of the prototype dosimeter is a blend of radiation-hard peroxide-cured polysiloxane plastic doped with scintillating agent P-Terphenyl and wavelength-shifter BisMSB. The prototype detector was tested with 6 MV and 10 MV x-ray beams at Ohio State University's Comprehensive Cancer Center. A 3-D dose distribution was successfully reconstructed by a neural network specifically trained for this prototype. This report summarizes the material production procedure, the material's water equivalency investigation, the design of the prototype dosimeter and its beam tests, as well as the details of the utilized machine learning approach and the reconstructed 3-D dose distributions.


Assuntos
Dosímetros de Radiação , Radiometria , Humanos , Aprendizado de Máquina , Doses de Radiação , Água
12.
Niger J Clin Pract ; 24(6): 937-942, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-34121744

RESUMO

AIMS: The objective of this study was to discuss the outcomes of the oncology patients whose PET/CT scans show incidental focal thyroid 18F-FDG uptake. METHODS: This retrospective analysis examined 2575 18F-FDG PET/CT scans from 1803 patients with no known thyroid cancer history. The survival rates were analyzed for patients with and without cytopathological evaluation. RESULTS: Increased metabolic activity of the thyroid was detected in 96 patients. Of those, 72 were diagnosed with a focal uptake of 18F-FDG and 24 subjects had a diffuse uptake. All 72 patients with a focal uptake were referred for ultrasound (US) and fine-needle aspiration cytology (FNAC). Of those patients, 44 were admitted for US and 16 underwent FNAC. The mean SUVmax was 16.0 ± 7.97 for patients with malignant lesions and 3.24 ± 0.88 for patients with benign lesions (p = 0.023). The mortality rate was higher in the patients who were not evaluated with FNAC. CONCLUSION: Patients with incidental focally increased thyroid 18F-FDG accumulation on PET/CT are known to have a high risk of malignancy. These patients require additional diagnostic procedures to distinguish the underlying pathology. However, the clinical condition of these patients will be the primary concern when performing these procedures.


Assuntos
Fluordesoxiglucose F18 , Neoplasias da Glândula Tireoide , Humanos , Achados Incidentais , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada , Estudos Retrospectivos , Neoplasias da Glândula Tireoide/diagnóstico por imagem
13.
Adv Mater ; 33(17): e2005166, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33759267

RESUMO

Semiconductor heterostructures of multiple quantum wells (MQWs) have major applications in optoelectronics. However, for halide perovskites-the leading class of emerging semiconductors-building a variety of bandgap alignments (i.e., band-types) in MQWs is not yet realized owing to the limitations of the current set of used barrier materials. Here, artificial perovskite-based MQWs using 2,2',2″-(1,3,5-benzinetriyl)-tris(1-phenyl-1-H-benzimidazole), tris-(8-hydroxyquinoline)aluminum, and 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline as quantum barrier materials are introduced. The structures of three different five-stacked perovskite-based MQWs each exhibiting a different band offset with CsPbBr3 in the conduction and valence bands, resulting in a variety of MQW band alignments, i.e., type-I or type-II structures, are shown. Transient absorption spectroscopy reveals the disparity in charge carrier dynamics between type-I and type-II MQWs. Photodiodes of each type of perovskite artificial MQWs show entirely different carrier behaviors and photoresponse characteristics. Compared with bulk perovskite devices, type-II MQW photodiodes demonstrate a more than tenfold increase in the rectification ratio. The findings open new opportunities for producing halide-perovskite-based quantum devices by bandgap engineering using simple quantum barrier considerations.

14.
Cureus ; 13(12): e20557, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-35103136

RESUMO

BACKGROUND: Rhinoplasty is one of the most challenging esthetic operations as it demands an optimal esthetic and practical outcome. Complications of rhinoplasty may occur intraoperatively or postoperatively during wound healing and contracture. OBJECTIVES: The aim of this study was to assess the complications of septorhinoplasty at King Abdullah Medical City Hospital (KAMCH) and to evaluate the satisfaction scores of the patients and the doctors after primary and revision septorhinoplasty. MATERIALS AND METHODS: In the last five years, 32 out of 425 patients (7.5%) underwent revision septorhinoplasty to correct complications of the previous operations performed at KAMCH. This is a retrospective single descriptive study that included Saudi patients aged 18 years and above who underwent primary and revision septorhinoplasty at KAMCH from January 2015 to March 2020. We reviewed the medical records of the patients to identify postoperative complications. Data were analyzed using SPSS statistical program (versions 7 and 8; SPSS Inc, Chicago). RESULTS: The mean age of the 32 patients who underwent revision septorhinoplasty was 26 ± 8.5 years. Most of the complications involved the nasofrontal angle and the columellolabial angle. Statistically significant improvements in the satisfaction scores of the patients and the doctors were observed before the first surgery, after the first surgery, and after the second surgery (P = 0.000 for each time point). CONCLUSION: The satisfaction levels of the patients and the doctors improve after the second surgery.

15.
ACS Appl Mater Interfaces ; 12(15): 17881-17892, 2020 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-32188240

RESUMO

The unique properties of hybrid organic-inorganic perovskites (HOIPs) promise to open doors to next-generation flexible optoelectronic devices. Before such advances are realized, a fundamental understanding of the mechanical properties of HOIPs is required. Here, we combine ab initio density functional theory (DFT) modeling with a diverse set of experiments to study the elastic properties of (quasi)2D HOIPs. Specifically, we focus on (quasi)2D single crystals of phenethylammonium methylammonium lead iodide, (PEA)2PbI4(MAPbI3)n-1, and their 3D counterpart, MAPbI3. We used nanoindentation (both Hertzian and Oliver-Pharr analyses) in combination with elastic buckling instability experiments to establish the out-of-plane and in-plane elastic moduli. The effect of Van der Waals (vdW) forces, different interlayer interactions, and finite temperature are combined with DFT calculations to accurately model the system. Our results reveal a nonmonotonic dependence of both the in-plane and out-of plane elastic moduli on the number of inorganic layers (n) rationalized by first-principles calculations. We discuss how the presence of defects in as-grown crystals and macroscopic interlayer deformations affect the mechanical response of (quasi)2D HOIPs. Comparing the in- and out-of-plane experimental results with the theory reveals that perturbations to the covalent and ionic bonds (which hold a 2D layer together) is responsible for the relative out-of-plane stiffness of these materials. In contrast, we conjecture that the in-plane softness originates from macroscopic or mesoscopic motions between 2D layers during buckling experiments. Additionally, we learn how dispersion and π interactions in organic bilayers can have a determining role in the elastic response of the materials, especially in the out-of-plane direction. The understanding gained by comparing ab initio and experimental techniques paves the way for rational design of layered HOIPs with mechanical properties favorable for strain-intensive applications. Combined with filters for other favorable criteria, e.g., thermal or moisture stability, one can systematically screen viable (quasi)2D HOIPs for a variety of flexible optoelectronic applications.

16.
ACS Energy Lett ; 5(1): 117-123, 2020 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-32055687

RESUMO

Halide perovskites have shown great potential for light emission and photovoltaic applications due to their remarkable electronic properties. Although the device performances are promising, they are still limited by microscale heterogeneities in their photophysical properties. Here, we study the impact of these heterogeneities on the diffusion of charge carriers, which are processes crucial for efficient collection of charges in light-harvesting devices. A photoluminescence tomography technique is developed in a confocal microscope using one- and two-photon excitation to distinguish between local surface and bulk diffusion of charge carriers in methylammonium lead bromide single crystals. We observe a large dispersion of local diffusion coefficients with values between 0.3 and 2 cm2·s-1 depending on the trap density and the morphological environment-a distribution that would be missed from analogous macroscopic or surface measurements. This work reveals a new framework to understand diffusion pathways, which are extremely sensitive to local properties and buried defects.

17.
J Phys Chem Lett ; 11(3): 716-723, 2020 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-31933373

RESUMO

Metal halide perovskite quantum wells (PQWs) are quantum and dielectrically confined materials exhibiting strongly bound excitons. The exciton transition dipole moment dictates absorption strength and influences interwell coupling in dipole-mediated energy transfer, a process that influences the performance of PQW optoelectronic devices. Here we use transient reflectance spectroscopy with circularly polarized laser pulses to investigate the optical Stark effect in dimensionally pure single crystals of n = 1, 2, and 3 Ruddlesden-Popper PQWs. From these measurements, we extract in-plane transition dipole moments of 11.1 (±0.4), 9.6 (±0.6) and 13.0 (±0.8) D for n = 1, 2 and 3, respectively. We corroborate our experimental results with density functional and many-body perturbation theory calculations, finding that the nature of band edge orbitals and exciton wave function delocalization depends on the PQW "odd-even" symmetry. This accounts for the nonmonotonic relationship between transition dipole moment and PQW dimensionality in the n = 1-3 range.

18.
Artigo em Inglês, Espanhol | MEDLINE | ID: mdl-31734189

RESUMO

Tumor thrombus is an intravascular malign tumor extension that may occur in various types of cancer. Hepatocellular carcinomas (HCC) are common causes of malign thrombus. The presence of a malign thrombus due to HCC has a dismal prognosis, which affects treatment choices. We present three cases of tumor thrombi due to advanced HCC detected by 18F-FDG PET/CT.


Assuntos
Carcinoma Hepatocelular/diagnóstico por imagem , Carcinoma Hepatocelular/secundário , Fluordesoxiglucose F18 , Neoplasias Hepáticas/patologia , Células Neoplásicas Circulantes , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada , Compostos Radiofarmacêuticos , Idoso de 80 Anos ou mais , Humanos , Masculino , Pessoa de Meia-Idade , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada/métodos
19.
Glob Chall ; 3(11): 1900042, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31692950

RESUMO

Carbon nanodots (C-dots) are emerging as a new type of promising agent in anticancer, imaging, and new energy. Reports as well as the previous research indicate that certain C-dots can enhance targeted cancer therapy. However, in-depth mechanisms for such anticancer effect remain unclear. In this work, treatment provided by the date pit-derived C-dots, exhibits significant DNA damage; Annexin V/7-AAD-mediated apoptosis, and G2/M cell cycle arrest in prostate cancer cells. The application of C-dots to the cell generally leads to acidulation of the cell medium, cooperated with membrane compact. The date pit-derived C-dots are observed inhibiting the horseradish peroxidase. Moreover, the C-dots disrupt likely through nucleotide excision DNA repair at low dose during DNA ligation step suggesting the antimicrobial effect and targeting Pim-1, EGFR, mTOR, and DNA damage pathways in cancer cells. For the first time the detailed and novel mechanisms underlying the C-dots, derived from the date-pit, as an efficient, low-cost, and green nanomaterial are reveled for cancer therapy and anti-infection.

20.
Nano Lett ; 19(6): 3535-3542, 2019 06 12.
Artigo em Inglês | MEDLINE | ID: mdl-31009227

RESUMO

Semiconductor quantum well structures have been critical to the development of modern photonics and solid-state optoelectronics. Quantum level tunable structures have introduced new transformative device applications and afforded a myriad of groundbreaking studies of fundamental quantum phenomena. However, noncolloidal, III-V compound quantum well structures are limited to traditional semiconductor materials fabricated by stringent epitaxial growth processes. This report introduces artificial multiple quantum wells (MQWs) built from CsPbBr3 perovskite materials using commonly available thermal evaporator systems. These perovskite-based MQWs are spatially aligned on a large-area substrate with multiple stacking and systematic control over well/barrier thicknesses, resulting in tunable optical properties and a carrier confinement effect. The fabricated CsPbBr3 artificial MQWs can be designed to display a variety of photoluminescence (PL) characteristics, such as a PL peak shift commensurate with the well/barrier thickness, multiwavelength emissions from asymmetric quantum wells, the quantum tunneling effect, and long-lived hot-carrier states. These new artificial MQWs pave the way toward widely available semiconductor heterostructures for light-conversion applications that are not restricted by periodicity or a narrow set of dimensions.

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